Process for the preparation of surface-treated calcium carbonate material and use of same in the control of organic material in an aqueous medium

ABSTRACT

The present invention relates to a process for the production of a surface-treated calcium carbonate, the use of this surface-treated calcium carbonate in a process for the control of organic material in an aqueous medium, as well as to a composite of surface-treated calcium carbonate and organic material, such as a composite of surface-treated calcium carbonate and to the use of such a composite.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional of U.S. application Ser. No. 13/807,940, filed Feb.6, 2013, which is a U.S. national phase of PCT Application No.PCT/EP2011/061869, filed Jul. 12, 2011, which claims priority toEuropean Application No. 10170110.0, filed Jul. 20, 2010 and U.S.Provisional Application No. 61/500,171, filed Jun. 23, 2011, thecontents of which are hereby incorporated by reference.

The present invention relates to a process for the preparation ofsurface-treated calcium carbonate material, the surface-treated calciumcarbonate material obtained thereby, the use of this surface-treatedcalcium carbonate material for the control of organic material, as wellas to a composite of surface-treated calcium carbonate and organicmaterial and its uses.

Organic material characterised as “sticky”, i.e. presenting a relativelyhigh degree of tackiness and/or adhesiveness relative to certainsurfaces, presents problems in a variety of contexts. Oily organicmaterial, such as petroleum and its derivatives, released in naturalaqueous mediums have been associated with environmental catastropheswhen such substances adhere to the internal or external surfaces ofspecies (e.g. to bird wings or lung surfaces) in contact with thisenvironment.

A number of treatments to remove oil from the surface of water have beendeveloped. Sawdust, peat fibers, diatomaceous earth, expanded perliteand vermiculite have all been used to soak up oil, as mentioned in U.S.Pat. No. 3,414,511. In view of the same aim, U.S. Pat. No. 3,855,152 andU.S. Pat. No. 4,011,175 refer to the use of expanded perlite mixed withasphalt, cellulose fibers and clay to form a mixture to be spread on oilspills.

The prior art also refers to surface-treated materials for this purpose,as in U.S. Pat. No. 3,382,170, wherein expanded perlite coated withsilicone is employed. In JP 74 45,467, perlite granules are coated withpolypropylene to produce oleophilic-hydrophobic granules for thetreatment of oil spills, while U.S. Pat. No. 3,696,051 refers to the useof vermiculite coated with a metallic cyclopentadienyl compound. In U.S.Pat. No. 2,464,204, a mineral aggregate such as sand is mixed withpetroleum asphalt and fuel oil and heated to form aggregated particleshaving a coating of solid carbon. U.S. Pat. No. 5,035,804 refers tocompositions comprising a fine grained particulate material, such asexpanded perlite or vermiculite, or sand, coated with anoleophilic/hydrophobic layer comprising sulfur, a metallic sulphate, analkali metal nitrate, and burned hydrocarbon oil.

Sticky organic materials, including for example silicone rubbers anddefoamers, also present a problem in the paper industry, where “pitchproblems” or “stickies problems” are known to occur, reported mainly asa deposition of organic sticky material coming out of water suspensioneither onto the papermaking equipment or as spots in the paper webitself.

The primary fibre source in papermaking is wood, which is reduced to itsconstituent fibres during pulping by combinations of grinding, thermaland chemical treatment. During this process the natural resin containedwithin the wood is released into the process water in the form ofmicroscopic droplets. These droplets are referred to as pitch. Problemsarise when colloidal pitch becomes destabilised from the originalemulsion form and is deposited on the surfaces in the wet-end circuit ofa paper mill, where the particles can form agglomerates, whicheventually break loose and appear as visible spots in the paper, rangingfrom yellow to black in colour.

Today, increasingly, papermaking pH is either neutral or slightlyalkaline, such that the removal of pitch is no longer an automaticcorollary of the use of alum. The increase in pH to pseudo-neutral is agrowing trend in mechanical papers and so the study of pitch removalunder these conditions is also of growing importance. Moreover,mechanical pulps carry over much more dissolved and colloidal matterthan chemical pulps and recycled pulps.

For completeness, the Applicant would like to mention the followingpatent applications in its name referring to pitch control. WO2008/077877 mentions a wet-ground bentonite and talc that is useful totarget white pitch. WO 2008/113839 refers to a process for the controlof pitch in an aqueous medium, wherein surface-reacted natural calciumcarbonate or an aqueous suspension comprising surface-reacted calciumcarbonate and having a pH of greater than 6.0 measured at 20° C., isadded to the medium, wherein the surface-reacted calcium carbonate is areaction product of natural calcium carbonate with carbon dioxide andone or more acids.

Furthermore, the Applicant would like to mention the following patentapplications in its name referring to surface-treated calcium carbonatefor use in plastic applications. WO 2005/121257 refers to a dry mineralpigment characterised in that it contains a product formed in situ bythe multiple reaction between a calcium carbonate and one or moremoderately strong to strong H₃O⁺ ion donators, gaseous CO₂ and one ormore compounds of formula R—X, where R—X represents a carbonaceousradical and X represents groups such as carboxylic, amine, hydroxyl,phosphonic, or their mixtures. WO 2008/125955 mentions a process for thepreparation of a treated mineral filler product having reducedvolatiles, where the process comprises the steps of treating at leastone dry mineral filler with at least one Group II or Group III salt of aC₈ to C₂₄ aliphatic monocarboxylic acid to produce an intermediatemineral filler product, followed by treating the intermediate mineralfiller product with at least one C₈ to C₂₄ aliphatic monocarboxylic acidto produce a treated mineral filler product. Finally, WO 2010/023144refers to a treated mineral filler product comprising: at least onemineral filler and a treatment layer located on the surface of saidmineral filler(s), where said treatment layer comprises at least onesaturated C₈ to C₂₄ aliphatic carboxylic acid; and at least one diand/or trivalent cation salt of one or more saturated C₈ to C₂₄aliphatic carboxylic acid, where the weight ratio of all of saidaliphatic carboxylic acid salt(s):all of said aliphatic carboxylicacid(s) is from 51:49 to 75:25; and said treatment layer is present inan amount of at least 2.5 mg/m² of said mineral filler.

Lastly, the Applicant would mention unpublished European patentapplications 09167246.9 and 10151846.2, which mention the use of AMP andPEI, respectively, as additives in a mineral suspension used in order toincrease the suspension pH while limiting conductivity changes.Unpublished European patent application 09178228.4 mentions the use ofmonoalcohol primary alkanolamines as biocide enhancers, whileunpublished European patent application 10157099.2 mentions modifiedpolyalkyleneimines as flotation aid.

Talc is accepted as an effective control agent for pitch deposits andhas been used in the treatment of oil spills. It is assumed that talcreduces tackiness of organic substances such as pitch and petroleum, bycovering the surfaces of their oily agglomerates.

However, as it is necessary to target not only organic material residingat the surface of an aqueous medium, but also colloidal organic materialthat is dispersed within this environment, it is desirable to provide atreatment agent in the form of an aqueous suspension. Treatment agentssuch as talc present the drawback that they must be extensivelysurface-treated and/or mechanically sheared in order to becomesufficiently wetted to enter the bulk of the aqueous phase.

Therefore, there is a continuous need for alternative economic materialsthat are readily available, which may be provided in the form of anaqueous suspension and which are capable of controlling organic materialboth within and on the surface of aqueous systems.

The above objective has surprisingly been solved by the inventiveprocess for the preparation of calcium carbonate materialsurface-treated with one or more salts of a C₅-C₂₈ fatty acid, thesurface-treated calcium carbonate material obtained thereby, and theaddition of this surface-treated calcium carbonate material or anaqueous suspension comprising this surface-treated calcium carbonatematerial to an aqueous medium, in order to control the organic materialcontained in the aqueous medium.

The product obtained by the control process, that is to say a compositematerial formed of surface-treated calcium carbonate material andorganic material, is also an object of the present invention. Suchcomposite materials may find a variety of applications, including as afiller in paper.

For the purpose of the present invention, “control” of an organicmaterial in an aqueous medium shall mean (1) the reduction of thetackiness of this organic material, and/or (2) the association of thisorganic material to form a composite, and/or (3) the reduction of theaqueous phase chemical oxygen demand (COD). The latter may be measuredas in the Example section below. The formation of a composite isevaluated by a decrease in turbidity of the aqueous medium, and may bemeasured as described in the Examples section below.

The process for the preparation of surface-treated calcium carbonatematerial according to the present invention comprises the followingsteps:

-   -   a) providing at least one calcium carbonate-containing material;    -   b) providing at least one salt of a C₅-C₂₈ fatty acid selected        from the group comprising mono-alcohol primary alkanolamine        salts, polyethyleneimine salts, and mixtures thereof;    -   c) treating said calcium carbonate-containing material of        step a) by contacting it with said fatty acid salt(s) of step        b);    -   d) obtaining a surface-treated calcium carbonate material.

Preferably, the calcium carbonate of said calcium-carbonate containingmaterial is selected from the group comprising ground natural calciumcarbonate, dolomite, precipitated calcium carbonate and mixturesthereof. Said calcium carbonate may be present in said calcium-carbonatecontaining material in combination with further minerals, such as talcand/or mica.

Dolomite refers to dolomite mineral and is calcium magnesium carbonate,i.e. CaMg(CO₃)₂. Dolomite mineral is found either in dolomite rock,consisting essentially entirely of dolomite, or in association withcalcium carbonate in dolomitic limestone.

“Ground natural calcium carbonate” (GNCC) in the meaning of the presentinvention is a calcium carbonate obtained from natural sources, such aslimestone, marble or chalk, and processed through a treatment such asgrinding, screening and/or fractionising by wet and/or dry, for exampleby a cyclone, classifier or centrifuge.

“Precipitated calcium carbonate” (PCC) in the meaning of the presentinvention is a synthesized material, generally obtained by precipitationfollowing reaction of carbon dioxide and lime in an aqueous medium or byprecipitation of a calcium and carbonate ion source in water. PCC may bemetastable vaterite, stable calcite or aragonite. In one embodiment,this PCC may be ground.

Said GNCC or PCC may be surface reacted to form a surface-reactedcalcium carbonate, which are materials comprising GNCC and/or PCC and aninsoluble, at least partially crystalline, non-carbonate calcium saltextending from the surface of at least part of the calcium carbonate.Such surface-reacted products may, for example, be prepared according toWO 00/39222, WO 2004/083316, WO 2005/121257, WO 2009/074492, unpublishedEuropean patent application with filing number 09162727.3, andunpublished European patent application with filing number 09162738.0.

Said calcium-carbonate containing material of step a) preferablycontains at least 50%, preferably at least 90% by weight of calciumcarbonate relative to the total weight of said calcium-carbonatecontaining material.

In a preferred embodiment, 10 to 90%, preferably 30 to 85%, morepreferably 60 to 80% by weight of the calcium carbonate materialparticles present, prior to treatment, a particle diameter of less than1 μm as measured according to the measurement method in the Examplessection herebelow.

In another preferred embodiment, 80 to 97%, preferably 90 to 98% byweight of the calcium carbonate material particles present, prior totreatment, a particle diameter of less than 2 μm as measured accordingto the measurement method in the Examples section herebelow.

In another preferred embodiment, the median diameter of the calciumcarbonate material particles presents, prior to treatment, a d₅₀ valueof from 0.4 to 5 μm, preferably of from 0.5 to 1 μm, as measuredaccording to the Example section hereafter.

In a preferred embodiment, the calcium carbonate material presents a BETspecific surface area before treatment of 1 to 200 m²/g, preferably of 7to 15 m²/g, as measured according to the measurement method provided inthe Examples section herebelow.

In one embodiment, said calcium-carbonate containing material of step a)is provided in the form of an aqueous suspension. In this embodiment,said suspension has a content of calcium carbonate containing materialwithin the range of 1 wt.-% to 79 wt.-%, more preferably of 3 wt.-% to78 wt.-%, even more preferably of 55 wt.-% to 75 wt.-%, based on theweight of the suspension. Though said calcium-carbonate containingmaterial may be dispersed with a dispersant or pre-ground with agrinding aid, such as a polyacrylate-based dispersant or grinding aid,it is preferred that said calcium-carbonate containing material insuspension be free of dispersant or grinding aid. If dispersant orgrinding aid is employed, it is preferred that it is dosed in a lowamount, i.e. from 0.02 to 0.5% by dry weight relative to the dry weightof calcium-carbonate containing material. In an alternative embodiment,dispersant or grinding aid is present in an amount corresponding to 0.05to 1 mg/m² of calcium-carbonate containing material, the m² ofcalcium-carbonate containing material being determined based on the BETsurface area measurement described in the Examples section hereafter.

According to the present invention, at least one calcium carbonatematerial is surface treated with one or more salts of a C₅-C₂₈ fattyacid selected from the group comprising mono-alcohol primaryalkanolamine salts, polyethyleneimine salts and mixtures thereof.

In a preferred embodiment, said salt of a C₅-C₂₈ fatty acid is a salt ofa C₆-C₂₄ fatty acid, more preferably a salt of a C₈-C₁₈ fatty acid.

In a preferred embodiment, said salt of a C₅-C₂₈ fatty acid is a salt ofa fatty acid having an iodine number of less than 5 g I₂/100 g of fattyacid salt. The iodine number determination is well-known to the skilledman, and namely involves iodine addition to a 100 g fatty acid samplefollowed by back-titration of the surplus iodine solution with sodiumthiosulphate.

In a preferred embodiment, said salt of a C₅-C₂₈ fatty acid is a salt ofa linear fatty acid if said fatty acid is a C₆-C₉ fatty acid.

In a most preferred embodiment, said salt of a C₅-C₂₈ fatty acid is ablend of palmitic acid salt(s) and stearic acid salt(s), preferably in aweight ratio based on the fatty acids of palmitic acid:stearic acid of2:1 to 1:2.

Said salt of a C₅-C₂₈ fatty acid is preferably 30 to 110 mole %neutralised with said mono-alcohol primary alkanolamine and/or apolyethyleneimine. In the case of a polyethyleneimine salt, said salt ofa C₅-C₂₈ fatty acid is preferably 35 to 45 mole % neutralised. In thecase of a mono-alcohol primary alkanolamine, said salt of a C₅-C₂₈ fattyacid is preferably 90 to 100 mole % neutralised. The mole %neutralisation is determined based on the number of moles of fatty acidto be neutralised. A mole % neutralisation in excess of 100 mole % meansthat excess mono-alcohol primary alkanolamine and/or a polyethyleneimineis added during the neutralisation process.

If said salt of a C₅-C₂₈ fatty acid is a polyethyleneimine salt, it ispreferred that said polyethyleneimine be linear. In this case, saidpolyethyleneimine preferably has a molecular weight of from 140 to 700g/mol, and preferably of from 146 to 232 g/mol. For the purpose of thepresent invention, the “molecular weight” of linear polyethyleneimine isdirectly calculated from the respective chemical formula.

Said polyethyleneimine may also be a branched polyethyleneimine, whichpreferably has a molecular weight of from 500 to 50 000 g/mol, and morepreferably of from 800 to 25 000 g/mol. The “molecular weight” ofbranched polyalkyleneimines prior to modification in the meaning of thepresent invention is the weight average molecular weight as measured bylight scattering (LS) techniques.

If said salt of a C₅-C₂₈ fatty acid is a monoalcohol primaryalkanolamine salt, said monoalcohol primary alkanolamine is preferablyselected from the group comprising ethanolamine, propanolamines,butanolamines, pentanolamines and mixtures thereof.

In a most preferred embodiment, said salt of a C₅-C₂₈ fatty acid is a1-amino-2-propanol salt of a C₅-C₂₈ fatty acid.

Said calcium carbonate-containing material(s) is preferably treated witha total of 0.1 to 3 wt. %, preferably 0.5 to 2 wt. %, based on the dryweight of said calcium carbonate-containing material(s), of said salt(s)of C₅-C₂₈ fatty acid(s).

In an alternative embodiment, said calcium carbonate-containingmaterial(s) is treated with a total of 0.2 to 5 mg of said salt(s) ofC₅-C₂₈ fatty acid(s) per m² of calcium carbonate-containing material,and preferably with 0.5 to 2 mg of said salt(s) of C₅-C₂₈ fatty acid(s)per m² of calcium carbonate-containing material, where said m² ofcalcium carbonate-containing material is determined based to the BETmeasurements made as described in the Examples section herebelow.

Said calcium-carbonate containing material may be treated by contactingsaid salt(s) of C₅-C₂₈ fatty acid(s) with said calciumcarbonate-containing material in either a dry or wet, e.g. aqueous,environment.

This dry or wet treatment process may take place by mixing and/orgrinding said C₅-C₂₈ fatty acid salt(s) with said calciumcarbonate-containing material at a temperature of from 5 to 150° C.

Grinding may be accomplished in a grinder and may result from anautogenous grinding operation, in which the particles for grinding aresubjected to mutual impacts, or may result from additional impacts withone or more other grinding media, such as grinding balls, grinding barsor grinding spindles. Such grinding with grinding media may take place,for example, in a ball-mill, such as manufactured by the companyDynomill, a vibration grinder or a wheel grinder. Depending on the typeof grinding, said grinding may take place in a stationary or rotarygrinding chamber. Said salt(s) of C₅-C₂₈ fatty acid(s) may be added tothe calcium-carbonate containing material feed and/or into the grindingchamber, prior to and/or in the course of the grinding process.

In the case of a ball-mill, the grinding balls which are employedpreferably have a Brinell hardness of between 510 and 600.Preferentially they are made of iron, such as iron-based alloys withmolybdenum or chromium, porcelain and/or silicates, and they have anaverage ball diameter of between 0.1 and 5 mm, preferentially of between0.2 and 3 mm, and more preferentially of between 0.5 and 5 mm. Accordingto another preferred aspect, these grinding balls are present in aweight ratio relative to the material for grinding contained in theball-mill of between 10:1 to 100 to 1, preferably of 20:1 to 80:1, morepreferably from 30:1 to 60:1.

In the case where the treatment process is a wet treatment process, theaqueous treatment environment may be provided by providing said calciumcarbonate-containing material in the form of an aqueous suspensionand/or by providing said salt(s) of C₅-C₂₈ fatty acid(s) in the form ofan aqueous solution or suspension.

Said salt solution or suspension preferably has a solids content of 5 to50% by weight. It is also possible to use a dry salt; in such a case,said salt is preferably liquid at 23° C.

If the treatment process is a wet treatment process, the obtainedaqueous suspension can, in one embodiment, be dried, thereby obtainingthe surface-treated calcium carbonate in the form of granules or apowder.

If the treatment process is a dry treatment process, the obtainedgranules or powder may be introduced into an aqueous medium, therebyobtaining the surface-treated calcium carbonate in the form of anaqueous suspension.

As mentioned above the surface-treated calcium carbonate materialobtained by the process of the present invention is a further object ofthe present invention.

Preferably, the surface-treated calcium carbonate material comprises 97to 99% by weight of a calcium carbonate material, 0.1 to 3% by weight ofmonoalcohol primary monoalkanol amine and/or polyethyleneimine salt(s)of C₅-C₂₈ fatty acid(s) and 0 to 1.5% by weight of calcium and/ormagnesium salt(s) of C₅-C₂₈ fatty acid(s).

Furthermore, it has surprisingly been found that the surface-treatedcalcium carbonate material obtained by the process according to thepresent invention may advantageously be used for controlling organicmaterial in an aqueous medium.

Thus not only the use of the surface-treated calcium carbonate materialobtained by the process according to the present invention forcontrolling organic material in an aqueous medium is an aspect, but alsoa process for the control of organic material in an aqueous medium,wherein said surface-treated calcium carbonate material or an aqueoussuspension comprising surface-treated calcium carbonate material isadded to the medium, wherein the calcium carbonate is surface treatedwith one or more salt(s) of a C₅-C₂₈ fatty acid, selected from the groupcomprising mono-alcohol primary alkanolamine salts and polyethyleneiminesalts.

Said organic material(s) in an aqueous medium that may be controlledthrough the use of said surface-treated calcium carbonate include anylipophilic organic material(s), such as petroleum, petroleumderivatives, stickies, silicone rubbers, white pitch (such as issuedfrom latex), pitch and mixtures thereof.

For the purpose of the present invention, organic material that may becontrolled by the present invention includes pure organic materialsand/or materials in which one or more inorganic materials are partiallyor fully covered by an organic material.

Petroleum, also referred to as crude oil, comprises a mixture ofhydrocarbons of various weights, notably paraffins, naphthenes, aromaticand asphaltic(s) hydrocarbons, along with sulphur- and/or nitrogen-and/or oxygen containing organics. The exact composition of petroleum isoften a function of the reservoir from which it is extracted. It maygenerally be extracted from oil wells or from oil or tar sands.

Petroleum derivatives include organic compounds obtained by crude oildistillation or refining, and organic compounds obtained from thermal orcatalytic cracking of fractions of crude oil.

“Stickies” in the meaning of the present invention are intended to referto sticky organic materials resulting from paper recycling. During paperrecycling, hot melt glues, binders and other thermoplastic materials,for example from book-backs and adhesives tape or from silicone baseddefoamers may lead to the formation of so-called “stickies”. Thesemostly exhibit varying degrees of hydrophobicity. They tend to bepliable organic materials, such as styrene-butadiene binders, latex ingeneral which is also termed “white pitch” when causing problems in thepaper machine wet end, rubber, vinyl acrylates, polyisoprene,polybutadiene, hot melts, etc. Under certain conditions, these compoundscan become tacky and deposit in the paper machine. The deposits can leadto breaks in the paper or appear as visible spots, often darkened byheat, in the final product, resulting in loss of paper quality anddowntime to clean the paper machine.

The chemical composition of pitch is generally divided into four classesof lipophilic components: i) fats and fatty acids, ii) steryl esters andsterols, iii) terpenoids, and iv) waxes. The chemical compositiondepends on the fibre source, such as variety of tree, and on theseasonal growth from which the sample is produced.

The formation of pitch can be described conceptually as developing viathree main mechanisms. The first mechanistic route is the formation ofan organic film of material, which can be transparent or translucent.Its thickness varies according to its concentration and the film needs anucleus to form an initial coalescence. This type of pitch, as itsformation mechanism suggests, is called filmy. The second type of pitchis one that is able to coagulate and form globules of 0.1-1.0 μmdiameter, and thus is termed globular pitch. The third type of pitchcommonly developed is an agglomerated, or pitch ball form and is oftennoticed in systems having the greatest problems with pitch deposition.The balls formed are of 1-120 μm diameter. In the filmy or globularstate, the pitch does not generally cause problems, but onceagglomerates have been formed then paper quality problems start tooccur.

In a preferred embodiment, the pitch in said aqueous medium is non-ionicand/or anionic.

The total amount of such organic material in the aqueous medium prior tothe addition of said surface-treated calcium carbonate, evaluated basedon the Chemical Oxygen Demand (COD), is preferably from 1 000 to 5 000mg O₂/dm³, as measured according to the measurement method provided inthe Examples section herebelow.

The pH, as measured in the Examples section herebelow, of the aqueousmedium prior to the addition of said surface-treated calcium carbonateis preferably greater than 6, more preferably greater than 7.

In the process for the control of organic material according to thepresent invention, the surface-treated calcium carbonate is added to theorganic material-containing aqueous medium by any conventional feedingmeans known to the skilled person. The surface-treated calcium carbonatecan be added as an aqueous suspension, e.g. the suspension describedabove. Alternatively, it can be added in solid form, e.g. in the form ofgranules or a powder or in the form of a cake. Within the context of thepresent invention, it is also possible to provide an immobile phase,e.g. in the form of a cake or layer, comprising the surface-treatedcalcium carbonate, the aqueous medium running through said immobilephase.

Preferably, the surface-treated calcium carbonate is suspended in theorganic material-containing aqueous medium, e.g. by agitation means. Theamount of surface-treated calcium carbonate depends on the type oforganic material to be controlled. Preferably, said surface-treatedcalcium carbonate is dosed in the aqueous medium in an amountcorresponding to 0.05 to 5 wt.-%, more preferably 0.1 to 1 wt.-% andmost preferably 0.15 to 0.5 wt.-% per 1,000 mg O₂/dm³, wherein said mgO₂/dm³ is determined by the COD measurement method described in theExamples section herebelow.

In one preferred embodiment of the present invention, thesurface-treated calcium carbonate is added to a pitch containing aqueousmedia, such as mechanical pulp, e.g. ground wood, TMP (thermo mechanicalpulp), or chemothermomechanical pulp (CTMP), as well as chemical pulp,e.g. kraft pulp or sulphate pulp, or recycled pulp used in the papermaking process.

Pitch containing pulp which can be subjected to the process of thepresent invention particularly comes from wood pulp, which is the mostcommon material used to make paper. Wood pulp generally comes fromsoftwood trees such as spruce, pine, fir, larch and hemlock, but alsosome hardwoods such as eucalyptus and birch.

The pitch, which can be controlled according to the present inventionmay comprise such species as fats and fatty acids, steryl esters andsterols, terpenoids, and waxes. The chemical composition depends on thefibre source, such as variety of tree, and on the seasonal growth fromwhich the sample is produced.

Optionally, additives can be added to the water sample to be treated.These might include agents for pH adjustment, etc.

After the adsorption is completed, the composites formed ofsurface-treated calcium carbonate, organic material and optional furthermaterials can be separated from the aqueous medium by conventionalseparation means known to the skilled person such as sedimentation,centrifugation and filtration.

The composite material formed on contacting said surface-treated calciumcarbonate with said organic material in an aqueous medium is also anobject of the present invention.

Such a composite material finds uses including the use as a filler inpaper.

In the case where the composite material is formed following the contactof said surface-treated calcium carbonate with sulphur-comprisingpetroleum or sulphur-comprising petroleum derivatives, this compositematerial presents the distinct advantage that when burned, this sulphuris reduced.

The following examples will illustrate the present invention, but arenot intended to limit the invention in any way.

EXAMPLES Measurement Methods

BET Specific Surface Area of a Material (m²/g)

BET specific surface area values were determined using nitrogen and theBET method according to ISO 9277.

Particle Size Distribution (Mass % Particles with a Diameter<X) andWeight Median Grain Diameter (d₅₀) of Particulate Material

Weight median grain diameter and grain diameter mass distribution of aparticulate material were determined via the sedimentation method, i.e.an analysis of sedimentation behaviour in a gravimetric field. Themeasurement was made with a Sedigraph™ 5100.

The method and the instrument are known to the skilled person and arecommonly used to determine grain size of fillers and pigments. Themeasurement is carried out in an aqueous solution of 0.1% by weight ofNa₄P₂O₇. The samples were dispersed using a high speed stirrer andultrasonic.

Suspension pH Measurement

The pH of a suspension was measured at 23° C. using a Mettler Toledo™Seven Easy pH meter equipped with the corresponding Mettler Toledo™ pHexpansion unit and a Mettler Toledo InLab® 730 Expert Pro pH electrode.

A three point calibration (according to the segment method) of theinstrument is first made using commercially available buffer solutionshaving pH values of 4, 7 and 10 at 20° C. (from Aldrich™).

The reported pH values are the endpoint values detected by theinstrument (the endpoint is when the measured signal differs by lessthan 0.1 mV from the average over the last 6 seconds).

Weight Solids (% by Weight) of a Material in Suspension

The weight of solids is determined by dividing the weight of the solidmaterial by the total weight of the aqueous suspension.

The weight of the solid material is determined by weighing the solidmaterial obtained by evaporating the aqueous phase of suspension anddrying the obtained material to a constant weight.

Gravimetric Analysis of a Suspension (mg/dm³)

For a gravimetric analysis, a 100 cm³ sample of aqueous phase was placedinto a pre-weighed aluminium beaker and dried in an oven (90° C., 24 h)to get a total amount of non-volatile residue in the aqueous phase, i.e.any organic and inorganic material which was not adsorbed on the mineralsurface.

Suspension Turbidity Analysis (NTU)

45 cm³ samples were used to analyse turbidity caused by colloidal pitchparticles by means of a NOVASINA 155 Model NTM-S (152). This instrumenttransmits light in the near infrared spectrum through an optical fibreprobe where the emerging beam is scattered by small particles insuspension. Light scattered back at 180° is collected by paralleloptical fibres in the probe and focused onto a photo-diode. Theresulting signal is amplified and displayed directly in NephelometricTurbidity Units (NTU), defined as the intensity of light at a specifiedwavelength scattered, attenuated or absorbed by suspended particles, ata method-specified angle from the path of the incident light, comparedto a synthetic chemically prepared standard. Interference from ambientlight is eliminated by the adoption of a modulated transmission signal,removing the need for light-tight sample handling systems.

Chemical Oxygen Demand (COD, mg O₂/dm³)

2 cm³ samples were used to make chemical oxygen demand (COD) analyses,which give a value for the total organic content, i.e. the non-adsorbedorganic material. The COD analysis expresses the quantity of oxygennecessary for the oxidation of organic materials into CO₂ and wasmeasured using a Lange CSB LCK 014, range 1000-10000 mg dm⁻³ with a LASA1/plus cuvette.

Streaming Current Detector Equivalency (SCD, μEq/g)

SCD titration measures the charge of the colloidal fraction insuspension and was evaluated using Mütek PCD-02 instrumentation.

Polyelectrolyte Titration (PET, μEq/g)

The polyelectrolyte content in the aqueous suspension is determinedusing a Memotitrator Mettler DL 55 equipped with a Phototrode DP 660commercialised by Mettler-Toledo, Switzerland. The measurements of thepolyelectrolyte content was carried out by weighing a sample of thecalcium carbonate suspension into a titration vessel and diluting saidsample with deionized water up to a volume of approximately 40 ml.Subsequently, 10 ml of 0.01 M cationicpoly(N,N-dimethyl-3,5-dimethylene-piperidinium chloride) (PDDPC;obtained from ACROS Organics, Belgium) are slowly added under stirringinto the titration vessel within 5 min. and than the content of thevessel is stirred for another 20 min. Afterwards the suspension isfiltered trough a 0.2 μm mix-ester membrane filter (Ø47 mm) and washedwith 5 ml of deionized water. The thus obtained filtrate is diluted with5 ml of phosphate buffer pH 7(Riedel-de Haën, Germany) and than 0.01 Mof a potassium polyvinylsulfate (KPVS; obtained from SERVAFeinbiochemica, Heidelberg) solution is added slowly to the filtrate totitrate the excess of cationic reagent. The endpoint of titration isdetected by a Phototrode DP660, which is adjusted to 1200 to 1400 mV indeionized water, prior to such measurement. The charge calculation iscarried out according to the following evaluation:

$\mspace{20mu}{Q_{atro} = {\frac{\left( {\left( {V_{PDDPC}*t_{PDA}} \right) - V_{KPVS}} \right)*\left( {- 1000} \right)}{E_{P}*{Fk}}\left\lbrack {\mu\;{Val}\text{/}g} \right\rbrack}}$$\mspace{20mu}{w_{atro} = {- {\frac{Q_{atro}}{K_{DM}*100}\mspace{11mu}\lbrack\%\rbrack}}}$${{{Calculation}\mspace{14mu}{of}\mspace{14mu}{the}\mspace{14mu}{optimal}\mspace{14mu}{sample}\mspace{14mu}{weight}\text{:}\mspace{14mu} E_{P}} = \frac{60}{w_{DM}*K_{DM}*{Fk}}}{Calculation}\mspace{14mu}{of}\mspace{14mu}{adapted}\mspace{14mu}{sample}\mspace{14mu}{weight}\mspace{14mu}{for}\mspace{14mu} 4\mspace{14mu}{ml}\mspace{14mu}{consumption}\text{:}\mspace{14mu}{\quad{E_{4\mspace{14mu}{ml}} = \frac{E_{1}*6}{\left( {10 - V_{{KPVS},\; 1}} \right)}}}$

ABBREVIATIONS

E_(P)=sample weight [g]

w_(DM)=Dispersing agent content in [%]

K_(DM)=Dispersing agent constant [μVal/0.1 mg dispersing agent]

Fk=Solids content [%]

V_(PDDPC)=Volume PDDPC [ml]

V_(KPVS)=Volume KPVS [ml]

t_(PDDPC)=Titer PDDPC

E_(DM)=Dispersing agent weight [mg]

Q=Charge [μVal/g]

w_(atro)=Dispersing agent content atro [%]

E₁=Sample weight of experiment to be optimised [g]

V_(KPVS,1)=experimental consumption KPVS [ml] of experiment to beoptimised

Ions in Solution (ppm)

The ions in an aqueous medium were measured by ion chromatography usinga Dionex DX 120 Ion-Chromatograph.

Zeta Potential (mV)

Zeta potential was measured using a Zetasizer Nano ZS at 25° C. Analysisof the resulting data was conducted in accordance with the Smoluchowskicoagulation equation according to M. Smoluchowski: “Drei Vorträge überDiffusion, Brownsche Molekularbewegung and Koagulation vonKolloidteilchen”, (Phys Z, 17 (1916) 557-571 and 585-599).

Materials

Sample 1

Sample 1 contained the minerals talc, chlorite and magnesite andoriginated from Finland. The talc purity was of about 97%, which wasconfirmed by FT-IR [Perkin Elmer Spectrum One Spectrometer] and X-rayfluorescence (XRF) [ARL 9400 Sequential XRF] analyses.

It was ground with a jet-mill resulting in a BET specific surface areaof 9 m²g⁻¹ and a d₅₀ of 2.2 μm.

Sample 2

284 g of stearic acid, 89.2 g of 2-Amino-2-methyl-1-propanol (AMP) and100 g of water were mixed together to form a solution of AMP-stearicacid salt (hereafter “FAS1”). 5,600 g in respect to dry mineral matterof a 70 wt. % solids slurry of marble of Norwegian origin, in which 75%by weight of the particles had a particle diameter of less than 1 μm anda specific surface of 9.2 m²/g, was prepared by dispersing anapproximately 70 wt. % solids filter cake of low solids ground (at 20wt. % in absence of dispersant) marble of such finesse using 0.5 wt. %in respect to dry marble of a sodium salt of acrylic acid-maleic acidcopolymer (having a Mw=12 000 g/mol), at room temperature. AMP-stearicacid salt “FAS1” was added at a temperature of 60° C. to the slurry,which was also heated to 60° C., to reach a fatty acid salt addition of1.0 wt. % based on the dry weight of calcium carbonate. The final solidsof the suspension was 68 wt. %, the Brookfield viscosity at 100 rpmmeasured after 1 min was 300 mPa·s and the pH at 23° C. was 8.34. Thisproduct represents a product of according to the invention.

Sample 3

10.12 g of octanoic acid, 6.27 g of 1-amino-2-propanol (AMP) and 17 g ofwater were mixed together to form a solution of AMP-octanoic acid salt(hereafter “FAS2”). The total of FAS2 was then mixed, at roomtemperature, with 2,000 g in respect to dry mineral matter of a 20 wt. %solids (wet ground at 20 wt % in absence of dispersant) marble ofNorwegian origin, in which 75% by weight of the particles had a particlediameter of less than 1 μm, and having a specific surface of 9.2 m²/g.This corresponded to a fatty acid salt addition of 0.82% by dry weightbased on the dry weight of calcium carbonate. This product represents aproduct of according to the invention.

Sample 4

14.1 g of a mixture of coco nut fatty acids (consisting of 5 wt. %caprylic acid, 6 wt. % capric acid, 52 wt. % lauric acid, 20 wt. %myristic acid, 9 wt. % palmitic acid, 2 wt. % stearic acid, 4 wt. %oleic acid and 2 wt. % linoleic acid), 6.6 g of 1-amino-2-propanol (AMP)and 5 g of water were mixed together to form a solution of AMP-coco nutfatty acid salt (hereafter “FAS3”). The total of FAS3 was then mixed, atroom temperature, with 2 000 g, in respect to dry weight of mineralmatter, of a 20 wt. % solids (wet ground at 20 wt. % in absence ofdispersant) suspension of marble of Norwegian origin, in which 75% byweight of the particles had a particle diameter of less than 1 μm, andhaving a specific surface of 9.2 m²/g. This corresponded to a fatty acidsalt addition of 1.03% by dry weight based on the dry weight of calciumcarbonate. This product represents a product of according to theinvention.

Sample 5

10.12 g of octanoic acid and 0.7 g of tetraethylenetriamine (TETA) weremixed together to form TETA-octanoic acid salt/octanoic acid mixture(hereafter “FAS4”). The total of FAS4 was then mixed, at roomtemperature, with 2 000 g, in respect to dry weight of mineral matter,of a 35 wt. % solids (wet ground at 35 wt % in absence of dispersant)suspension of marble of Norwegian origin, in which 75% by weight of theparticles had a particle diameter of less than 1 μm and a specificsurface of 9.2 m²/g, at room temperature. This corresponded to a fattyacid/fatty acid salt addition of 0.54% by dry weight based on the dryweight of calcium carbonate. This product represents a product ofaccording to the invention.

Sample 6

5 g of FAS 1 was used to dry treat 500 g of dry ground Italian marblehaving a medium diameter of 1.7 μm. The dry treatment was made in a MTIMixer activated at 3 000 rpm while heating the product to 130° C. Thiscorresponded to a fatty acid salt addition of 1.0% by dry weight basedon the dry weight of calcium carbonate. This product represents aproduct of according to the invention.

Aqueous Medium Comprising Organic Material

Pitch-Comprising Aqueous Medium

6.0 kg of the fresh wet pulp (3.2 w/w % solids content) were taken fromthe accept of the screen at a temperature of 90° C. before the bleachingstep (peroxide bleaching) at an integrated pulp and paper mill inSwitzerland in February 2010. The process water at the sampling positionwas only circulated in the thermo-mechanical pulp (TMP) plant andcontained no fillers. The TMP thus obtained and used as a pitch sourcefor the following experiments consisted of 70 wt.-% spruce, the restbeing composed of fir and a small part of pine. The pH of the pulpsample was 6.1 at 25° C. The pulp was wet pressed through a filter of 2μm pore size (filter paper, circular 602 EH). The filtrate, hereafter“TMP Filtrate”, was recovered and analysed; the results are reported inTable 1 below.

TABLE 1 Value Property Turbidity (NTU) 406 COD (mg O₂/dm³) 4070 pH 7.16Conductivity (mS/cm) 0.922 Gravimetry (mg/dm³) 3160 Zeta potential (mV)−8.3 +/− 5.36 PET (μEq/g) −1.62 SCD (μEq/g) −0.75 Ions in solution (ppm)Na⁺ 131 K⁺ 41 Ca²⁺ 43 Mg²⁺ 5 Cl⁻ 12 SO₄ ²⁻ 63

Tests in Pitch-Comprising Medium

2.0 g of each of the above listed materials were introduced into flasksalong with 200 g samples of TMP Filtrate and with 18.0 g of water. Theflasks were then sealed and agitated in a rotating mill (rotating atapproximately 100 rpm) for a time period of 2 hours at room temperature.

Thereafter, the contents of each of the flasks were introduced into aRotina 420 centrifuge, rotating with a relative centrifuge force of 2580 RCF, and centrifuged for a period of 15 minutes.

Each of the recovered supernatants were analysed for turbidity, COD,gravimetry and ion balance.

TABLE 2 Sample 1 2 3 4 5 Comparative (CO)/ CO IN IN IN IN Invention (IN)Talc Turbidity 53% ± 43% ± 19 ± 18% ± 15% ± (normalized) 2% 2% 1% 4% 1%100% corresponds to 350 NTU ± 10 NTU COD 90% ± 92% ± 87% ± 86% ± 88% ±100% corresponds to 1% 2% 4% 2% 3% 3644 mg O₂/dm³ ± 90 mg O₂/dm³

The above results show that the surface-treated calcium carbonate of thepresent invention performs as well or better than talc in order tocontrol wood pitch.

Tests in Oil-Comprising Medium

Prior Art:

600 g of demineralised water was introduced into a glass beaker; then,20 g of high pressure ASE 55 327/ASE transmission oil (from OL, Bern,Switzerland) was added to form a layer on the top surface of the water.Thereafter, 20 g of talc (Sample 1) was added on top of the oil. Thebeaker contents were weakly agitated manually using a glass rod.

The oil was mostly bound by the talc mineral and settled to the bottomof the glass beaker. The water bulk and surface remained visibly cloudy.

Invention:

The same protocol as above was repeated, adding 20 g of Sample 6 inplace of talc.

The oil was mostly bound by the surface-treated calcium carbonatemineral and settled to the bottom of the glass beaker. The water bulkbecame visibly clear and no oil could be observed on the water surface.

The invention claimed is:
 1. A surface-treated calcium carbonatematerial obtained by treating at least one calcium carbonate-containingmaterial with at least one salt of a C₅-C₂₈ fatty acid(s) selected fromthe group consisting of (i) a mono-alcohol primary alkanolamine salt ofa C₅-C₂₈ fatty acid(s), (ii) a polyethyleneimine salt of a C₅-C₂₈ fattyacid(s), and (iii) a mixture thereof, to obtain the surface-treatedcalcium carbonate material.
 2. The surface-treated calcium carbonatematerial according to claim 1, comprising 97 to 99% by weight of acalcium carbonate material, 0.1 to 3% by weight of monoalcohol primarymonoalkanol amine and/or polyethyleneimine salt(s) of C₅-C₂₈ fattyacid(s) and 0 to 1.5% by weight of calcium and/or magnesium salt(s) ofC₅-C₂₈ fatty acid(s).
 3. The surface-treated calcium carbonate materialaccording to claim 1, wherein the calcium-carbonate containing materialcomprises ground natural calcium carbonate, dolomite, precipitatedcalcium carbonate or any mixture thereof.
 4. The surface-treated calciumcarbonate material according to claim 1, wherein the calcium-carbonatecontaining material contains at least 50% by weight of calcium carbonaterelative to the total weight of the calcium-carbonate containingmaterial.
 5. The surface-treated calcium carbonate material according toclaim 1, wherein the calcium-carbonate containing material contains atleast 90% by weight of calcium carbonate relative to the total weight ofthe calcium-carbonate containing material.
 6. The surface-treatedcalcium carbonate material according to claim 1, wherein 30 to 85% byweight of the calcium carbonate material has a particle diameter of lessthan 1 μm.
 7. The surface-treated calcium carbonate material accordingto claim 1, wherein 60 to 80% by weight of the calcium carbonatematerial has a particle diameter of less than 1 μm.
 8. Thesurface-treated calcium carbonate material according to claim 1, whereinthe calcium carbonate material has a d₅₀ value of from 0.4 to 5 μm. 9.The surface-treated calcium carbonate material according to claim 1,wherein the calcium carbonate material has a d₅₀ value of from 0.5 to 1μm.
 10. The surface-treated calcium carbonate material according toclaim 1, wherein the calcium carbonate material has a BET specificsurface area of 1 to 200 m²/g.
 11. The surface-treated calcium carbonatematerial according to claim 1, wherein the calcium carbonate materialhas a BET specific surface area of 7 to 15 m²/g.
 12. The surface-treatedcalcium carbonate material according to claim 1, wherein the calciumcarbonate material is provided in the form of an aqueous suspension. 13.The surface-treated calcium carbonate material according to claim 1,wherein the calcium carbonate material comprises 0.05 to 1 mg dispersantor grinding aid per m² of calcium-carbonate containing material.
 14. Thesurface-treated calcium carbonate material according to claim 1, whereinthe salt of a C₅-C₂₈ fatty acid(s) is a salt of a C₆-C₂₄ fatty acid. 15.The surface-treated calcium carbonate material according to claim 1,wherein the salt of a C₅-C₂₈ fatty acid(s) is a salt of a C₈-C₁₈ fattyacid.
 16. The surface-treated calcium carbonate material according toclaim 1, wherein the salt of a C₅-C₂₈ fatty acid(s) has an iodine numberof less than 5 g I₂/100 g of fatty acid salt.
 17. The surface-treatedcalcium carbonate material according to claim 1, wherein the salt of aC₅-C₂₈ fatty acid(s) is a salt of a linear fatty acid if the fatty acidis a C₆-C₉ fatty acid.
 18. The surface-treated calcium carbonatematerial according to claim 1, wherein the salt of a C₅-C₂₈ fattyacid(s) is a blend of palmitic acid salt(s) and stearic acid salt(s).19. The surface-treated calcium carbonate material according to claim 1,wherein the salt of a C₅-C₂₈ fatty acid(s) is a blend of palmitic acidsalt(s) and stearic acid salt(s) in a weight ratio of palmiticacid:stearic acid of 2:1 to 1:2.
 20. The surface-treated calciumcarbonate material according to claim 1, wherein the salt of a C₅-C₂₈fatty acid(s) is a C₅-C₂₈ fatty acid 30 to 110 mole % neutralized with amono-alcohol primary alkanolamine and/or a polyethyleneimine.
 21. Thesurface-treated calcium carbonate material according to claim 1, whereinthe salt of a C₅-C₂₈ fatty acid(s) is a C₅-C₂₈ fatty acid 35 to 45 mole% neutralized with polyethyleneimine.
 22. The surface-treated calciumcarbonate material according to claim 1, wherein the salt of a C₅-C₂₈fatty acid(s) is a C₅-C₂₈ fatty acid 90 to 100 mole % neutralized with amono-alcohol primary alkanolamine.
 23. The surface-treated calciumcarbonate material according to claim 1, wherein the salt of a C₅-C₂₈fatty acid(s) is a polyethyleneimine salt of a C₅-C₂₈ fatty acid(s),wherein the polyethyleneimine is a linear polyethyleneimine having amolecular weight of from 140 to 700 g/mol.
 24. The surface-treatedcalcium carbonate material according to claim 1, wherein the salt of aC₅-C₂₈ fatty acid(s) is a polyethyleneimine salt of a C₅-C₂₈ fattyacid(s), wherein the polyethyleneimine is a linear polyethyleneiminehaving a molecular weight of from 146 to 232 g/mol.
 25. Thesurface-treated calcium carbonate material according to claim 1, whereinthe salt of a C₅-C₂₈ fatty acid(s) is a monoalcohol primary alkanolaminesalt of a C₅-C₂₈ fatty acid(s).
 26. The surface-treated calciumcarbonate material according to claim 1, wherein the monoalcohol primaryalkanolamine is ethanolamine, propanolamine, butanolamine, pentanolamineor any mixture thereof.
 27. The surface-treated calcium carbonatematerial according to claim 1, wherein the salt of a C₅-C₂₈ fattyacid(s) is a 1-amino-2-propanol salt of a C₅-C₂₈ fatty acid.
 28. Thesurface-treated calcium carbonate material according to claim 1, whereinthe calcium carbonate material is treated with a total of 0.1 to 3 wt. %of the salt(s) of the C₅-C₂₈ fatty acid(s), based on the dry weight ofthe calcium carbonate-containing material.
 29. The surface-treatedcalcium carbonate material according to claim 1, wherein the calciumcarbonate material is treated with a total of 0.5 to 2 wt. % of thesalt(s) of the C₅-C₂₈ fatty acid(s), based on the dry weight of thecalcium carbonate-containing material.
 30. An aqueous medium comprisingthe surface-treated calcium carbonate material according to claim 1 forthe control of organic material in the aqueous medium.
 31. Papercomprising the surface-treated calcium carbonate material according toclaim 1.